Using backside passive elements for multilevel 3D wafers alignment applications

Abstract

Passive circuit elements are formed at surfaces of two integrated circuit wafers. The passive circuit elements are utilized to align the two integrated circuit wafers to form an integrated circuit wafer stack.

The invention claimed is: 
     
       1. A device comprising:
 a first integrated circuit die including:
 a first semiconductor layer; 
 a first dielectric layer on the first semiconductor layer; 
 a first inductor coil in the first dielectric layer; and 
 
 a second integrated circuit die coupled to the first integrated circuit die, the second integrated circuit die including:
 a second semiconductor layer; 
 a second dielectric layer on the second semiconductor layer; and 
 a second inductor coil in the second dielectric layer, the first inductor coil in direct physical and electrical contact with the second inductor coil. 
 
 
     
     
       2. The device of  claim 1  wherein the first dielectric layer is on a back side of the first semiconductor layer. 
     
     
       3. The device of  claim 1  wherein the first dielectric layer is on a front side of the first semiconductor layer. 
     
     
       4. The device of  claim 1  wherein the first inductor is aligned with the second inductor. 
     
     
       5. The device of  claim 1  wherein the first integrated circuit die is a SOI integrated circuit die comprising:
 a buried insulating layer adjacent to the first semiconductor layer; and 
 a third semiconductor layer adjacent to the buried insulator layer opposite the first semiconductor layer, the buried insulator layer separating the first semiconductor layer from the third semiconductor layer. 
 
     
     
       6. The device of  claim 5  comprising:
 a transistor formed on the third semiconductor layer; and 
 a metal via in the first semiconductor layer and the buried insulator layer, the metal via electrically connecting the first inductor to the transistor. 
 
     
     
       7. The device of  claim 1  wherein the first and second inductors comprise a radio frequency circuit. 
     
     
       8. The method of  claim 1  comprising an adhesive material on the first integrated circuit die, the adhesive material bonding the first integrated circuit die to the second integrated circuit die. 
     
     
       9. The method of  claim 1  wherein the first inductor coil includes a conductive bonding material that effects a eutectic bond between the first and second inductor coils. 
     
     
       10. An integrated circuit package including:
 a first integrated circuit die; 
 a first inductor coil on a first surface of the first integrated circuit die; 
 a second integrated circuit die coupled to the first integrated circuit die; 
 a second inductor coil on a surface of the second integrated circuit die, the second inductor coil being aligned with and in ohmic contact with the first inductor coil; 
 first control circuitry in the first integrated circuit die; 
 second control circuitry in the second integrated circuit die; 
 a first through via in the first integrated circuit die; and 
 a second through via in the second integrated circuit die, the second through via being electrically connected to the first through via, the first control circuitry and the second control circuitry being electrically coupled together by the first and second through vias. 
 
     
     
       11. The integrated circuit package of  claim 10  wherein the first integrated circuit die is an SOI integrated circuit die. 
     
     
       12. The integrated circuit package of  claim 10  wherein the first inductor coil is on a back side of the first integrated circuit die. 
     
     
       13. The integrated circuit package of  claim 10  wherein the first inductor coil is on a front side of the first integrated circuit die.